This truly is one of the major benefits of FOSS based solutions, but rarely an argument that gets a positive reaction from (non-hacker) end-user. It's a sales argument only to hackers (well, programmers in general, though to be a good programmer - instead of one in code-monkey-row - probably demands one to be hacker), and even for them only small part of everything useful they come to think they would like to have will materialize as their personal projects they feel worth their time...
Luckily here comes the benefit of numbers - if an app/feature/etc. is wanted enough the number of hackers willingly dedicating their time to provide free (most often as in, both, freedom *and* beer) end solutions will guarantee there are people to take up that specific thing. Though hackers will treat their own needs and then their peers needs primarily and the "obscure GUI'ish needs of end-users" (those with tight lips or bee in a bonnet, lighten up) are the last thing they want to work on the state of current FOSS environments, number of people working on them free, number of business efforts to improve them and people thus working on FOSS for pay, etc. will keep pretty much any/every feature that you might want as well as those you wouldn't want available for you.
And it's why I'd never buy a computer that limited what I can install on it without at least providing a way around it, provided I'm the owner/have the root/etc. if I have a say on it.
I bought an iPod once though - it was used, cost me 5 euros and I knew I could replace the OS with rockbox if I wanted. All I wanted of it was to use it as MP3 player though and even with having to convert my .ogg files to another codec and not being able to access and alter the song collection like just another usb flashdrive but with weird iTunes clones, such as gtkpod, I never got to change the OS. It didn't feel important enough, though it would have made it better for me - and I eventually would have gotten up to it, but it was stolen.
This was told just to explain I don't act black/white, but I am pretty heavily invested towards open and against closed systems - for me to choose more closed one the choice would have to be about something insignificant or it has to have major benefits over the more open choice. In this case I bought, without supporting apple, a nearly free product built around walled garden ecosystem I could replace at anytime if it bothered me too much. Plus there was no other takers for that iPod at the time.
I drank too much coffee.